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Year of the Diesel: Audi made the point and JCB Dieselmax underscores it: Diesel isnt just for trucks anymore

September 10, 2006

Photo by LAT Photographic

Add one for the Bonneville boys

At 360 mph, a mile passes in 10 seconds. For RAF Wing Commander Andy Greenmore accustomed to the velocity of a Tornado jet fighter or the supersonic Thrust SSC record carit must feel like a long time.

Green passed through the measured mile on the Bonneville salt flat in 9.842 seconds (365 miles per hour) in one direction on August 23, still accelerating when the JCB Dieselmax finished the mile. The front engine (there are two, one ahead and one behind the driver, each driving one axle) was too cold and stuttered during the acceleration pass on his backup run, which FIA speed record rules require that he completerunning in the opposite direction to balance out factors of wind or gradewithin an hour. So the return leg took 10.724 seconds, a mere 335 mph, for a two-way average of 350.092 mph, giving the British team a new world record for diesel machines. Green had set the record less than 24 hours earlier at 328.767 mph, toppling the previous FIA mark of 235.756 mph that American Virgil Snyder set in 1973.

Speed itself wasnt the challenge: When he went supersonic on the ground in 1997, Green ran the measured mile in under five seconds. But JCB Dieselmax was a whole new world. Wheel-driven rather than jet-propelled, pushing the limits of diesel engine and drivetrain technology, and on the salt rather than the dusty alkali desert at Black Rock in Nevada.

Theyre very different vehicles to drive, Green said. SSC, in a lot of ways, was more of a known quantity. Its engines were familiar, proven capable, and the worry was mostly aerodynamic. With Dieselmax, were taking two bigger, heavier engines that have just been developed and trying to put the power down through two transmissionsgetting them properly synchronizedand then to the tires on salt.

JCB is a heavy-equipment manufacturer that just started making its own engines two years ago. Dieselmaxs two powerplants are based on the JCB 444, a four-cylinder turbodiesel routinely installed in a backhoe/loader. Dieselmax was conceived as a showcase for the engine and British engineering generally, said owner Sir Anthony Bamford.

Dieselmax and Thrust SSC are connected by more than a shared pilotBamford called on advice from Thrusts creator Richard Noble and brought in SSC aerodynamicist Ron Ayers.

The engines are the cars raison dêtre. JCBs 444 is exceptionally stout, with a stiff block and a rigid bottom end in the interests of durability and quiet running. The company also claims it will meet emissions standards envisioned for the next 15 years.

Working with engineering firm Ricardo, which also helped develop the JCB 444, the company put this effort together in less than two years from the first idea to the runs on the salt. The actual build started only 10 months ago. Displacement on each engine was bumped up from 4.4 to 5.0 liters, a new high-pressure direct-injection system was developed, and turbo boost was set to 5.2 bar (75.4 psi) to compensate for the altitude at Bonneville: 4265 feet, where the air pressure is about 85 percent that at sea level. By comparison, Audis diesel-powered Le Mans winner runs at 3 bar and the production JCB 444 at 2 bar.

Each engine puts out 750 hp, or 150 hp per liter. Torque is 1106 lb-ft per engine, delivered to the ground by separate six-speed transmissions developed especially for the program and synchronized electronically. The engines emit a deep-throated, low-rpm roar.

The target design speed was 400 mph, and Green said after his record runs that the car was still pulling like a train and we still havent used sixth gear! The car used just over one gallon of diesel fuel on each runit has a 9 liter (2.37 gallons) tank. A run comprises six miles at full throttle and five to slow down.

Speaking of slowing down, the brakes are a new disc design that, rather than employing calipers, mounts hydraulic rams on each suspension upright which press a stator against the rotor. The car is four times the weight of an F1 car and designed to run nearly twice as fast. It also has parachutes, deployed after the record run.

One reason to stop at the teams 2006 goal of 350 mph is that the tires are only rated to 300. Like all salt-flat racers, JCB found that high-speed tires are hard to get. Theres little available for this small market (only some old-stock Goodyear-built Mickey Thompsons), and the fastest machine available on which to test tires can only spin them to 350 mph.

Asked if the team had considered pushing for 600 km/h (the 350-mph record equates to 563.418 km/h), Dr. Tim Leverton, Dieselmax project director and JCB group engineering director, asked what that would be in miles per hour (how charmingly British). Told it would be 372.6 mph, not much faster than the quickest one-way run, he thought a moment and said: Were going to go back and look over all the data; the tires look good at first glance, but we need to do a proper analysis. Right after the [record] run is not the time to take that decision.

Bamford said that to go faster, the team would need to enlist a tire manufacturer as partner. Thats the limiting factor at this stage. Other Bonneville racers are hoping that JCB enlists such a partner, because they, too, are limited by the available tires.

Will Green be available for a return engagement? It seems likely, barring intervention from what he calls my day job. In the almost nine years since SSC, Green has been stationed, briefly, in Iraq and led the British detachment in Kandahar, Afghanistan, but now anticipates reposting to the Ministry of Defense, whereas happens to aging pilotshell be flying a desk. A return to Bonneville could be enticing.

I hadnt even planned to do this one, he said. It was JCB [that] approached me; Richard [Noble] and Ron [Ayers] were already onboard. When they asked me, it took me all of about two seconds to say yes.

Thatd be one-fifth of a mile at 360 mph.

Photo by www.landspeedproductions.biz

JCB Dieselmax was not the first diesel streamliner to top 300 mph. That honor goes to Roy Lewis in his Chassis Engineering Special, powered by a 5.9-liter six-cylinder twin-turbocharged Cummins engine. It was built six years ago and has owned the Southern California Timing Association (SCTA)/Bonneville Nationals Inc. record for its class since 2002.

Lewis says he started shooting for 300 mph a couple years ago, and achieved the mark at 306.8 mph on Aug. 16, a week before Dieselmax went 350 mph. Two days later, JCB Dieselmax set its own SCTA/BNI record at 317 mph during Speed Week while warming up for its FIA effort, but runs in a different displacement class so Lewis class record stands.

The main difference between SCTA and FIA records is that SCTAwith more than 435 entries at Speed Week this yearfinds the FIA standard of making two runs in one hour impractical. Instead, all those who put up a one-way speed within reach of a record go to the head of the line for the next day to make their runs in the opposite direction.